Synchronizing means for multimotored airplanes



Oct. 7, 1952 T. A. BANNING, JR 2,612,956

SYNCHRONIZING MEANS FOR MULTIMOTORED AIRPLANES Filed Sept. 22, 1942 7Sheet s-Sheet 1 Oct. 7, 1952 T. A. BANNING, JR 2,512,956

SYNCHRONIZING MEANS FOR MULTIMOTORED AIRPLANES Filed Sept. 22, 1942 7Sheets-Sheet 2 7, 1952 'r. A. BANNING, JR Y 2,612,956

smcaaomzmc; MEANS FOR uummo'roasn AIRPLANES Filed Sept. 22. 1942 v '7Sheets-Sheet 4 FBI].

InvenTor':

Oct. 7, 1952 -r. A. BANNING, JR 2,612,956 syncnaourzmc MEANS FORMULTIMOTORED' AI'RPLANES Fiied Sept. 22, 1942 7 Sheets-Sheet 5 Oct. 7,1952 T. A. BANNING, JR 2,612,956

' syncaaomzma MEANS FOR MULTIMOTORED .qmppmss Filed Sept. 22, 1942 7'sheets-sheet s 'f Oct. 7, 1952 -r. A. BANNING, JR 2,612,955

SYNCHRONIZ ING MEANS FOR MULTIMOTORED AIRPLANES Filed Sept. 22, 1942'ISheets-Sheet 7 Patented Oct. 7, 1952 *fum'rso STAT ES PATENT) o1 =1E--q .SYNCHRONIZING? MEANS FOR MULTIQ orons!) ,AIRPLANES Thomas A. Banning,Jr., Chicago, lll. Application September 22, 1942,'Serial No. 459,336

"This invention concerns itself wlth" control of multi-motoredairplanes' especially controlof the speed, power, pitch of] propellerblades, and other functions related thereto." While the features hereindisclosed have beendevised especially with re ferenceto 'thefconditionsexisting in multi motored airplanes, it will be evident hereinafter (Cl.I'm-135.29)

that many of said features are also useful in connecztiori with othermulti-motoredvehicles or installationssuch as motor boats; but sinceI'have deyisedme present improvements with especialreference"to-airplane installations-and: since I have herein illustratedmy improvements asappliedto'an airplane installation I shall makeespecial reference-to such installations, butin so doing Iwishit'understood that I do not thereby I intend to;lixnit' myself,exceptasfrmayfdo so in the claimstofollowl -The power generatedby eachairplane motor is" delivered to; its individual propeller,-and-theusevfulworkthereof is t'obe absorbedby such pro peller; 'Such power isrepresented by the product ofangulai' velocity multiplied by torque} andof course theangular velocity is a direct function of speed inR.Thetorque absorbed bythe propeller at anygiven speed conditionwill"depend on the pitch settingof the blades ofsuch propeller; and ingeneral saidtorque may be; varied between substantially zero-ands.maximum for the installation by pitch adjustment. It is;

of course understood that many factors afiect the torque absorbed forany-given pitchsetting, such as atmospheric pressure (changing withelevation above sea-level), amount of contained moisture (with respectto dew point), and other' factors. Still, for'any selected condition thetorque ab sorbed will ibe -controllable by pitch control; so,

likewise,lfora given powerlinput to the propeller (delivery by V themotor) change of speed must be accompanied by change of pitcht orconversely, for at given speed condition; change of power mustbelaccompanied by change of pitch;

Each motor of .a multi-motored airplane re? h quires control of its gassupply,its speed; and its pitch of propeller (in addition touvariousother controls afiectingits operation), but: thethreefactorsjustenumerated may be grouped together for .relative functioning.Itis very, desirable to so control the several motors that normally theywill rotate at the, same speed (assuming they are all;of the same sizeand characteristic When the plane is iii-normal operation this conditionis represented by synchronizingpf, the speed oi the several motors, andsuchsynchronizing very desirable for various reasons. In some Gases itis also desirableto so control the, yariouspropellers that their pitchesare substantially; the

sam d n o l f oni r-t e p a assuming that all thepropellers are takingthe same"bite on the air; andunder. these condi tions the powers beingdeliveredby the several motors will also be synchronized. Thus we findthatunder certain normal operating conditions it is desirable tosychronizeboth speed and-power of the several motors.

There arise frequently, however, conditions under which synchronizationof power (pitch) is not required or even desirable, while neverthelessit remains desirable to synchronize speed. For example, in *the case ofa special maneuver, such asa power dive; it-Iriay be very desirable to*maintain the motors in synchronized speed, but still to be able toindividually; control their several torques. In this connection, also,it is extremely desirable tohave assurance that-at alltimes dur ing suchmaneuver all the motors will remain functioning normally, so that whenthe pilot suddenly'i makes a demand on the motors for power they willall-be functioning normally, and will not fail him at'a critical instanty-One principalobjectof the pre'sentinvention is tdprovide means forsynchronizing the speeds of themo'tors, either withorwithout'synchroniza tionof motor-powers. Inconnection with thesynchronization of motor speeds it is a further objectbf the inventiontounalre provision-tor maintaining such synchronization veryaccuratelyg'se tliat allmotors will always function, at substantiaily'the samesp'eed. It isia further object inthis connection to makeprovisionfor securing such synchronization over a wide range of motor speeds, asmaybeselected' by-th'e pilot Sometimes the synchronization maybe attamed"by use of one of the "motors as a fipilot" r motor, makingvprovision,for bringing th'e speeds of the remainingfmotors into' synchronismthere-, i

with"; but-"generally, anda preferably it' is desir able to provideaflfpilot line or frequency with whichuall theumotors are synchronized;thereby eliminating the possibility, of throwing theentireLsynchronizing plan outer-function in case or disabling 0f;thepi1ot, motor. -I have herein disclosed" means .for securing thesynchronizin in either ofitheseways; 1. j

.,A further objectin .connectionlwith the fore going is tomakeprovisionafor manual controboi! the synchronizing, speed; sov thatthe pilot or the,

plane may set his speed 1 control tor-thenspeed which he may select,whereupon all thecmotors I willbebrought and held severelylandl veryact-i i 1 curately-at that speed, and wherebyany depaL- ture orany motorfrom that speed willzbeximle, mediately corrected; automatically,byathehsyne-Q chronizlng apparatus, and ,the speed f of: such motorwill be againheld at, the selected speed; as f predetermined bythepilot. In thisconnection,

' slrab also, it is an object to provide visual indicating means to showthe pilot the speed for which he has set his control mechanism.

In connection with the foregoing it is an object of the invention tomake provision for simultaneously controlling all the motors as respectspeed, so that the pilot may, by a simple setting of a single controlelement, ensure synchronization of all the motors at the selected speed.There by the work imposed on the pilot is reduced to a minimum, and hehas merely to manipulate a.

single control, and has merely to watch a single instrument orindicator, to know, that, all the. jmotors have been brought to theselected speed,

and will be rigidly held at such speed automatically, and withoutfurther thought oroperation on his part.

, It is'afurther object of the invention to make provision for quicklydisconnecting any selected motor from the'sfynchronizing means, so thatat, any time the, pilot mayfcut-out any motor from the, automaticsynchronizing control, and there v after, treat such motor specially astospeed, o1" cut'it out of service entirely; and also to enable cuttingout suchmotor from thesynchronizing system 'incase of damage to suchmotor or otherwise. -Also, insuch case to make provision for enablingthe pilot to continue individual operation of motorif possible, and ifdesired. In thisc nnection it is also an object of the invention tqrnakeprovision for manual control of any blade pitches.

synchronizing control. In this connection, also, it is an object to makeprovision for very simply disconnecting any selected motor throttle, orall motor throttles from such gang control, so that such motor may beindividually controlled manually, or so that such HlOtOFIIlfiYbfiQlfiCQdunder the'jurisdiction of the automatic. synchronizing control.

Sometimes it may be found desirable to control the, speed of the motorsby control of propeller For'example, in case of provision of a powercontrol device (as hereinafter disclosed) inv connection with eachmotor, which power control device operates directly on the throttles ofthe motors, it may become desirable to control speed by controllingpitch, leaving the power undisturbed. I have therefore, as a furtherobject of my present invention, made provision forfspeed controliby,control offpi'tchfoi blades, securing the condition. of synchronismfbysuitable pitch control automatically.f In this" connection" I have alsomade provisioniorgoutt'ing outthe or all motors in case ofdamagev to thesynchronizing ameans, so that in such case the control of thefpowerplant of the plane manually maybe fi ne siin fi t v- General y t e speedc l me n i un 19. -o jthemo r't lqtt s, Opening d cl s them. Q? ather; aus n them. from, t to time, or continuously: under functioning of; thesynehro i ine-me h n sm- In er s fi l re newe -slant y: oio e h an or-pow r ndiu rds r m o it m b o ewith,-the-main throttle, and such smallthrottle ein pr-s fici n siz tom e a j tments. rom

o se ure. close s hron zi im n y 599;: a sm l l rrc t e, ere ai conuncti n.

tim to ,time; or continuously to maintain syn,-

6. 1? m: un norma y i pfi d fis of. d" justment-;,-required; Thesynchronizing, meansv actsfithen f on such trimming; throttle, the mainthrottle-remainingundisturbed. StilLin case of the arising ofalccndition; requiring-a1 greater change ofgasvflow: than can be handledby, such small; trimmlllgrthlOtue,.- itbecomes necessary to readjust,the main; throttle in order to. maintain theicondition, of synchronism;selected; I have therefore,-, and asa further I object of the inven:tion; aunade: provision for ensuring automatic changejor readjustment'ofthe main throttle,- in conjunction with abnormally large changes ofrequlrement;;in order to maintain the condition of syn'chronism. Itv isafurther object of the in! vention to ensure proper functioning of boththrottlesiof each motor. at .alltimes; and irrespective'aofwhether. thepower requirement is one of .increaseor decrease ascalled for.

1.2.111 COIIHBCtiOII'WiththB foregoing, it is a further object of .theinvention to: provide a manual control for the throttle of each motor,sothat in CESQfOf desirabilitysuch throttlemaybe manually adjusted. L"In this connection it"i's a further object' to provide-a gang controlfor the throttles ofiall motors, so that if'desired all motor throttles7 may be, simultaneously manually controlled, as

fonfexample, in case of disabling the automatic same-supply tank. or.line.

certained that in caseit' is desirable to measure several speedcontrolsfor the several motor'a' andi for manual control of the pitchesjof theseveral propellers, if desired.

In connection with the forego ng it is further object of the inventionto'makejprovisijon for either individual or gang control .of the pitchesof the several motor pr'opellers manually, .as jde sired.

. Generally the power. required'for 'pitch central of the propellerblades will be excessive for' direct manual operation, and it isdesirable for, the-alts rangement to include power operation;- of thebladeshifting means. Ihave herein-disclosed such power blade operation,pre ferably'by oilor otherfluid under pressure; and I havev provided,

asja furtherobject of the invention,;,meansfor ensuring such power orservo-motor means opera tion, either automatically or manuallycontrolled, as selected. In either case, however, the power directlyapplied, to the blade shifting mechanism sn Qv d d-by t o lor. h r fluidunder pre sure.-

I when t is desired to measure motor power, be-

ing theproduct of speed and torque,- such measure I may beeiiectedeither by meansto multiply, these functions; or otherwise. I Ihave ascertained-that the rateof fue1;1 low;to a motonoperatin undernormal; con itions ofrpower r quir men s an accuratemeasure ofthe powerbeing momentarily delivered by such, motor-:7, Thus,,in;the, caseqofv agasolinemotor, especially-of the large sizes being: used; for: airplaneoperations, say of upwards ofione;.,thousand, horse-power, the rate of:gas consumption ofxsuch motor, when operating under,

v normal loading conditions, is anaccurate measure motor powersuchmeasurement may-be eif'ected by use of 'asuitably calibrated meterplaced" in the fuel supply line of 'suchmotor, the rate'of shaftrotation of such meter beinga measure of rateof'fuel consumption,-andtherefore also a measure of powerb'eing generated. It is therefore afurther object or the present mangoes invention to make provision forcontrol of motor power by suitable control of throttleor propellerpitch, based on rate of fuel consumption; and

also is a further object to, if desiredjsynchronize all motors of theseries, as respects their several power deliveries, byuse ofsuitable-controlsof throttle and propellerpitchesfi I {When it isdesirableto synchronizepor control power-[such control may beeffected byvarying the propeller pitches, in'case the controlof throtties is to bereserved for control of speed; orby control *of throttles, in oasethecontrol-of pro-' peller'pitches is to bereserved for speed.= it is' afurther object of my present invention'to,

if'desired, synchronize or co'ntrol both speed and power'ot each motorofthe series, by suitable controls of both the throttles and thepropeller:

pitches;

In connection with the foregoing, I havealsoi made provisionforgindicating tothe pilot of the plane the power being delivered, orthe power which he determines shall be delivered, by each motorfs'o thathe may set his control devicefor power, and have assurancethateachinotor will befbrought to the selected conditioner operaticnfasso pre-determined.

Generally conditions of speed willbe controlled by control of throttlesetting, and conditions {of piiwe'rwill be 7 controlled by adjustment ofblade es." 1 have therefore, in oneiform ofmyim 1 c vention madeprovision for synchronizing sp ed automatically, by control ofthrottles, andffo'r' synchronizing of powers of the motors by centralsettings; and in a further or, modified. fornio'f my invention I havemade provision for synchronizingoi motor spe'ds by control of'pro-'peller -blade'p'itches, and for control of motor after.

of ja synchronous motor element of very simple construction and design,andone which isvery rugged and well adapted to meet rigorous oper--ating conditions. Such synchronous synchronizing-element operates inconjunction with a polyphase control circuit; the frequency of which1circuit'is'subject to control by the pilotyso thatby powers forsynchronization by control of throttles,

a sjbetween the motor speed and theme-selected;

speed (as ire-determined by the. pilot), it is, neeessary to provide ameans for securing proper comparison of the momentary motorspeed withthe pre-selected speed, and if there be any difien; erence between thesetwo, for making proper. compensation or adjustment of the proper eleement either the throttle or the blade pitch, as required; andfurthermore, it is necessary tomake provision. for ensuring continuousautomatic functioning of the throttle or the blade pitch, as required,based on such comparison, gandwithout attentionby or thought of thepilot. It is, afurtherobject of the present invention toprovide such,synchronizingmeans, and to effect proper connection thereof to theelements, to be compared,;,and: tobe controlled. .Further'moreyit isnecessary that such synchronizing elementbe so constitutedcthat it willfunction continuously, and. with sufficient force or effort toensurethe? proper iunctioningxof the throttle or theblade pitchadjustment means, as the case may be; sothat not only will accurate andcontinuous synchronous: control be effected, but also sothat the properpower may at all times be available-to ensurethat proper correction willbe efiected or pitchoperating means: i It isEan important object ofmypresent invention to. provide a synchronizing device which willadmirably'meet all the foregoing requirements, as-

well: as. others, :as will-presently appear hereinin the-throttleadjusting the frequency of such. circuit he there by adjusts also the'synchronousgfrequency of the}: control element and any-departure of thespeed of themotor,;or of the fuel meter, from such ad-.

justed frequency will immediately ensure opera tion of the synchronouslyoperatingelement to ensure correction of the setting of the throttle (orof the blade pitch) to bring about the, needed, compensation and restorethe "condition prism chronism.

In connection withthe foregoing it is a further" object of the inventionto provide a very simple form of synchronizing element, one which isvery" rugged in construction, onefwhich cangbe'fbullfi of 'suilicientpower. to ensurefproper functioning of the necessary elements, and onewhich'can bj built to a high degree of standardization, ahd or a've'ryaccurate operation. f I

and speed are to be controlled automatically,

make use of the same constructionof sync ron ze; ing element for bothfunctions, s0 as to reduce the number of standards of elements. whichwill be. required for a complete installation. I'nthis 'conii nection,generally each of these synchronizing" elements will be of.relativelysmall size, 'fo'rfex ample, two hundredfyvatts, butitfmay bevery rugge'dly built, and well Y adapted to meet Yvery arduousconditions of operation in service. f Otherfobjects and'uses of theinventionwill: appearfrom a detailed description .of the same,

which consists in the features of. construction and combinations ofparts hereinafter describedand l ime -i. I

. In the drawings:

Figure l shows a schematic diagram or layout,

for a four motor installation, being a founprgpeller installation, inwhich speed control. only is automatically eifected, for synchronizationto a control or pilot circuit, undericontrol of the plane pilot, thesynchronous control for; each motor operating on atrimming throttle forSuch: motor, the main throttle of such motor being, also properlyconnected andcontrolled sothatiit will function automaticallyto talgecare,of,-variationsof demand larger than cangbe accommodated by thetrimming throttle alone; there being; provided. also manualcontrols forthe several main throttles, either individually or in gang, and therebeingprovided also manual control :for the. pitches of. the severalpropeller blades by oil under. pressure, such blade .controls beingeither. in gang or individually as desired; suitable indie catinginstruments being provided for the several Itis-a further obiect'oftheinvention'to provide such synchronizing device in theiorm" connectionwith the foregoing, it ther object of the invention, when both power"memento;

Eigures ,2 and; 3;, looking in the; directions; of: the;

arrows;

Eigl re 5 shows asectionon the line 5--5; of Figures g and-3,lookinginthe directionsoi: the- PW L I 4 Figure 6 shows a. verticalsection througlr'a selected setting thereof;

, Figure. 7' shows a. horizontal. section. on the.

line} 1,l of. Figure; 6., looking in. the. direction of the arrows.showing the oil, delivery ports. and? the 5 corresponding. plugpassages;

Eisllre. 8 shows. a. horizontal. section. onv the v 1in,8-.--8;ofFigure.6,,- lookingin the directionof the arrows, showing the oil supplyports, and'jthe. corresponding plug passages;

\ Figure. 9.. shows. a, plan view corresponding to. Fi ures 1 Figure 10shows longitudinal vertical sectionl'through amsynchronizing element,embody ing 'certainof the featuresv of. the present inventioii'incorporating a three phase rotating. field element and being a sectiononthewli'ne, Ill-'40 of Figure 11, looking in the, direction. of, thear- QW J. i

Figure 11 shows a cross-section on. the line ll"--l'l of Figure 10,looking in the direction of, the. arrows;

Fig-l re 12 shows a longitudinal section through anoilipressureservo-motor suitable for. power operating thebla'degad'justing mechanisms of the propeller, being providedwitha valvewhich, when moved to a 'givenposition, ensures correspending v movementand. stoppage of the power element of such servo-motor attheipre-selected point to place and hold the ,bladesat;such;preselected"position; V such, servo-motor being suitablefor: use in connection withcertainembodiments "Off "the; present invention Figure 13 shows avertical section through another form of oil valve for use inconnectionv with the control of the oil pressure operated bladeshiftingelements when using certainembodiments of-mypresent'invention;

Figure 14 shows ahorizontal section on-the line'- I 4-14 of- Figure 13,lookinginthe direc-r tion of the-arrows;

Figure l-fi shows a horizontal 1 section onthe line l 5-1 5 oi -Fi'gure13; looking in the direction of -the arrows;

- Figure 16 shows a plan view of. the valveof l*"igures=13;14 and-; a

Figure= 17 shows a schematic diagram or lay outsi'mi-lartothat ofFigural, but incorporating speed controli for theseveral motors basedonause oiione of the. motors .as:a =control' or' pilot motor; samebeing.manuallyzcontrolled;and the other motors being brought to the.same-:rspeedi asthatofsuoh control. motor; speed being con-- trailed bythrottle controls; and; this :layout also. includes. control of: i the,pitches. of. the.- bladesLof such control or pilot motor manually-land.automatic: control. of the pitches; of ,theblades. of the other. motors.according; to .poiver;- so.-. that. the power being. delivered.- by.suchficontrolf." or: pilot? motor determines. the; powerswhich. will: bedelivered by; theother .motorszz. regulation thereof being by control ofpitches.; .ofi. their:

blades;

Figure 18:shows :aschematic;layoutgordiagramr. similar to thatrof;Figure; 17; butxinttheopresent case; usegisy made of afipilot. circuitforcontrol of, powers of all the motors, the. speed. oil-one? motorbeing nrcontrol or pilot motor being; controlled by pitch adjustmentthereof-manual 1y; andservingto control thespeeds of 'theother:

motorsby control'of the .pitches of their. blades;

Figure 19 shows aschematicdiagram: or: lay out. similar to those,previously explainei but in the presentcase; thereare provided two.pi-lot! polyphase yci'rcuits. the frequencies ofv which can. be.manually controlledby the pilot ofthe ;plane;. onev of. these. circuitsbeing for determination of motor speedsand the otherbein-gfordeterminetionoi'motor'powers;. the. speeds of alllmotorsz.

- being brought into synchronism withthe speed 'v control. circuit bythrottle. controls, and the; powers'of. all motors. being broughtinto/syn chronism with the power control circuit by..blade.vadjustments; and.

Figure 20. shows. aschematic diagram. orlay;

' outsimilar to. thatofFigure. l9, .butin the prese ent. case thespeeds, are controlled'by control; of; blade pitches. and .the powersvare controlledlib'y; control of. throttles.

Figqurea 1 showsa fragmentary portion. of.,one? of the layouts, beingthe husbar portion there.- of, .on enlarged scale to bettershow.tlie.con'nec' tionsthereof and thereto; and" Figure 1'? shows a'fragmentary cross-section.

through the electro -magnetically operated. brake;

for lockingla:synchronous'control device during;

certain conditions of operation. wherein such locking is or may bedesired. 1

Referring first toFigures 1'0 andlI' Ishallde' scribe atypicalsynchronizing unit embodying. certain of thefeatures'ofmy present.invention; and which; has been; devised to meet" thecon-'- ditionsexisting in the solution; of the" entire problem" herein set forth: Inthis case-lihave" provided a. rotating field polyphase' element(corresponding to: the; usual statorof: a syn chronous -motor) 59 inconjunction with a"=field' element:v 5i" rotatable relativelythereto:Both of" these elements are" rotatable in themselves, that is, with*respect to the frame element 52; as wel'l as" relatively-. To this endthe hold element 51 is carried by" a shaft" 53-; j ournalle'dat onepoint to the frame, as by the ball bearing 54v This fieldelementiseXcited-in'the usual manner by" the field coils 55; carried bythe po'le'pieces 56, sothat north and south polesa are generated I in the usual"manner; s'uita'blei slip rings 1 5 1* are prov-ided for" supply ofexciting-inur rent 1 to thesecoils from a point external to "thefieldelement."

The polyphaseelement 50 includes the lam'lnated' core of ring type-58set into the shell 58,- wh-ich- 'shell' is carried by the shaft section60 which reaches inthe opposite direction from the shaft 53; Thisshaftsection BU is suitabIy'joure nailed to: the frame 52; as lbytheball bearing ,6] and suitable slip rings'tz are providedfor'suppm of?three: phase current to .the windings: of? this elementvfi'flsConveniently. the: two. shafts.- 53 and" 60:, are;.1telescopediinrthe;central, portion .otfthe structuraiaszsliownnso:as to:provide averysturdy andswell; alignethstr'ucture; keeping; in: mind xthefactitlcxatgthegclearancesbetweenithe:twov elements smooth; andleasyrunning: of these parts relativelyto each other-p AS1851 matter." of:structural? con venience I have shown the pole pieces 56 of the,fleldrelement as being provided with the caps 66 which retain the coils55 in position on the .pole pieces, these coils being specially shapedto set together into a very compact form of structure ,as-shown. I havealso shown the polyphase element asprovided with the slots or tunnels 08for accommodation of the polyphase winding in well understood manner. Ideem it unnecessary to describe in detail the polyphase winding of thisunit, as same may. be of suitable scheme to provide a rotating field inthe ring element 58 in well understood manner. Probably in most cases,the'polyphase windings will be delta connected conditions theshaft 60be rotated at such synchronousspeed the polyphase element willremainr'stationary, notwithstanding that it is acro'tationuof-the shaft 60at synchronousspeed,

the polyphase element will remain stationary. If, I now there be adeparture of the speed of the shaft from such synchronous condition,then the polyphaseelement 50 will have to rotate either forward orbackward with respect to the frame 52 in order to maintain the requiredmag- :9.

jnetic. lock between the field and polyphase elements, due to thepresence of the rotating field 1 in -the:element 50, For example, if thespeed of shaft rotationiof theshaft 60 be lowered to 1750 R. P. therewill exist a differential of .50

R. as between the speed of the shaft 50 and .the" speed of the rotatingfield, and since theshaft speedis less than 'thespeed of themtatingfield it will be necessaryfor the element 50 :to rotate baokwardly at50R. P. M. in order to maintain the condition of synchronismras betweenthe field and polyphase elements, due to theimagnetic lock betweentheseparts. On the other hand, if the shaft speed of the shaft 60*weregreater than the synchronous speed, for ex ample; 1850 R. P. itwould be necessary for the element 50 to rotate forwardly at thedifferential of speeds, namely, 50 R. P. M. r

Now, according to one important feature of my present invention Imakeprovision for positively i'drivingly connecting one of the elements 50or f5'l to the motor shaft, as by a gear drive, and for 111811; These,propellers are generally provided ,tually free torotate in eitherdirection as needed. ,lnsotherwords, under the assumed conditions ofconnecting the other of said'elements to the device to be controlled,for example the motor "throttle, in such I manner that this differential:of speeds causes the proper correction to be made in such controlelement in order to bring the motonspeed to'the condition ofsynchronism, as dictated by the frequency of the rotating field of theelement 50, which inturn depends on the polyphase frequency supplied tosuch element.

I also provide means to supply such polyphase current at alpine-selectedfrequencyunder control of the plane pilot, or otherwise, so that he hasit inhispower at any time to determine the frequency of such polyphasesystem, and thereforeto determine the motor speed. I

-- "It shouldbe herementioned that either of the elements or 5| may beconnected tothe shaft asdesir'e'd, the other of said elements beingconwnected to the device to be controlled; but general- 1y the-shaft .60carrying the field element will I be connected to the motor sh t asmatter of convenience;

Now referring to Figure l, I xhave therein shown a typical four motorlayout, including the motors 69, 10,? ,II and 12,; These are providedwith their power shafts 13, I4, I5 and ML-respectively, and said shaftscarryor drive the propel- 1611's 11, 18, "I9 and in the wellunderstoodmanwith variable pitch blades, and-suitable, means to controlthepitchthereof; either singly Orin-gang.- In the layoutshown in Figure 1I-havershown the v oil,cylinders 8I,,-82, 83 and 8,4 for theseveralproupellers, said cylinders being provided: withtheroil lines-85-85, 81-438, 89-'90'and: 9I-e92, respec r tively; the;lines 85, 81, 89anddl being for :supply I of oil to increase pitch, and thelines 86,88,90 and oil-lines aregcarried to suitablecontrolmeans,

92 ,beingfor supply of oilto decrease pitchi 'Sai'd either automatic; ormanual so that the propeller pitches can be controlled from thecontrolstand. 1 I In the layout shown in Figure 1 these pitch controloil lines are brought to the valves 93, 04,

y95 and 96; and inFigureslfifll, B and 9. I have shown a typical form ofvalve "suitable forleffecting control of oil deliveries andreleasesiufrorn these lines. This valve includes the casing 91 'Where inis rockingly placed the plu evalve 98, which, plug valve has :the; stem:99 reaching out of! the top of thedevi'ce, andQp'rovided withthecontrol handle 100. A suitable-packinggland IOI may,1 if desired, beprovided at the point of stemuexit. The two lines (85-88, or 8'I- 88, or89'-90, opal-92,- asithe case maybe) are brought tothe ports I02 and I03of the casing;

and at otherfsuitablenpoints the casln'giis provided with other portsIMand l05nwhich are for supplyi.and return of oil :tothevalve; wFor.Iexamplewthe port: I04 may be .a return port,

and the port I05 a presure supply port. The plug 98, has a passage -I06extending acrossiv it at the plane of the ports I02and I03, and one endof -said passage is carried downtoathepla'ne "of the ports 1.04an'dil05, asshowir at I01. ,,Ali-

other passage IOBat right angles to'theepassage' I06 is located'attheplane lofuthe portsflfll, and I05, out of communication from thepassageilmi; and the ends of said passage I08 arelcarried uptofthe'plane of the ports I02 and I03, as shown at I 00 and II 0.., Theseveral ports and passages are sozformedthat laps between themareavoidedsci as to prevent cross flows ofloil. I

- =1 With l this .valve" arrangement, it, will be "seen that with theplug standing in the position of Figure 6 all ports are sealed, and theblade shift-- ing device to which the oil-lines are connected will beoil locked-against shift in either direction,'and oil ean neitheribessupplied to nor released from such blade shifting device. ,;-Byiturn-'ing thehandle I00 in one direction 'from such central. positionpressure oila I will I be delivered to oneof the on lines, and releaseoilzwillibe released from the other oil .line, .the pressure oil comingfrom the port I05'and the released oilibeing returned to the port I04;so that'the bladeishifting device will be'properly functioned undercontrol of such valve; and such functioning will continue as long as thevalve remains insuch shifted position, or. until the blades havebeencompletely shifted, either to the full feathering or the zero pitchposition. On theother hand, by turning the valve to a functioningposition, and quickly thereafter returning it toits 13 the wormgear I38;and theshaft53 of the control element-is provided with a worm I39meshing with such'worm gear to drive the same. I The frictiondrive fromthe worm gear I38 to the shaft 13.1 is of sufficient friction driveelleot to ensure proper movements of the shaft I31 (and throttle -l2llhwith movement of thegear I38 until said shaft reaches-either limit-pfits movement as limitedby either ofthe stops I41 or I48 presently tobedescribed. The shaft 60 ofsuch control element is provided with a gearI40which is geared to the power motor shaft, 13,14, I ar I6, as the casemay be, :so thatspeed of the shaft 60 of such'control element is alwaysexactly propor- .tional to power motor speed. The polyphase cur- .rentoi thepilot circuit" is delivered tothe polyyphase elementiilofthe-control device so that there-is created in such polyphase element aroworm I45. This motor I43 receivesdirectlcur I rent from the linesm andI32, through suitable control switching devices; and includeclin theseswitching devices are the followingz 'lj he trin ming throttle shaft I31carries at its bachend a swinging arm I46 which is adapteditostriketatlng, fieldwhose speed is determined by the jpilot control, asv willbe evident from theeiiplanationso far given. I a a a U Nowif the speedof the power motor is exa ctlyt thatpredetermined by the pilot, thepoly- ;phase' element 50 will remain stationary or: nonrotating, andthere wiilbe no rotative force; com -.-rnunica ted to the trimmingthrottle, so that fuel ,s pply ,to the power motor will continue run-.changed. Now if forsome reason thespeed of the powermotor departs fromsynchronism, for example, rises above synchronism the. element ,50willcommence. to rotate inonedirection or the other at a rate depending onthe amountlof ,suchdeparture-from synchronism; and such roa stop pin I41or I48 at one side of its-swing or the other, as the case may be, toarrest the swinging of the trimming throttle at its full position in:one direction or the other, and thereby prevent over-riding of suchthrottle. The trims ming shaft also carries another arm I49whieh has thecontact plate I50, connected to one side of the direct current supplysystem from the lines HI and I32; and there the provided the twostationary contacts I5I and I52 in position forengagement by saidcontact I50 at one or the other limit of swing of the trimmingthrottlaas the case may be, The motor I43 is a reversible direct current motorof convenient designand the contacts I5I and I52 are so connected tosaid motor that the:direction ofmotor rotatiomwill be determined bywhich of said contacts is mo.-

mentarily engaged by the swinging contact-Emile and I52 are connected tothe proper terminals of V [the motor by the leads I54 and I55 --(see,Eigtation will immediately commencea corrective turning of the triminingthrottle in the proper direction .tof restore the condition ofsynhronismr It isto be noted that such, corrective action will continueuntil complete synchronism has been attained; and if another departurefrom synchronism shouldoccur, either in the same or ,contrary direction,corrective action will at once commence, and will continue untilsynchronism has againbeenattained; In fact, normally there .willprobably lower a more or less. continuous ,corrective action, backandforth, in one direction orthe other, but always in proper direction,and .of-proper amount to restore synchronous condi- ,tion.- It is alsoto be noted that immediately ny departure from synchronous conditionoocurs, .a corrective action will. commence, and the rotation of {thetrimming throttle shaftwill con- 'tinue ,until complete correction hasoccurred.

Now ordinarily the amount of corrective action needed tofm aintain thecondition of synchronism jw i'll be relatively small, such as a fewpercent ofthe power being generated by the power motor, .orafewpercentcf the momentary synchronous speed Such corrections will behandled con- ;fyenie'ntly by a trimming throttle of relativelysmallsize. In case of large swings of departure [from 'synchronism,however, it will be evident ,thatthe trimming throttle may be movedclear ,overin the one direction .or the other without restoring thesynchronous condition; a and under 'tthese conditions it is necessary toprovide means to automatically effect further corrective action bymanipulation of the main throttle I I8. Such means I haveprovidedherein. To this end I .l provide the main throttleon a shaft I4] to which :Qsuchmain throttle is firmly connected; andthis 'shaftcarries by friction drive a worm gear,l42.

There is provided a small directcurrent motor,

ure 1). i

With this arrangement the following operations with one or the other ofthe stops I4'I' or I48: andat, the same timethecontact I will engage oneor the other of the contacts I5I or-I5 2,, as

the, case maygbe. 7 Since the condition of S nchronism has not yet beenattained'thepolyzphase element 50 of theysynchronizing device willcontinue to rotate, but thetworm gear I318 will slip on the shaft I3'Iduring this portion, of

theoperation.- -As soon as one or otherof the :contacts I5I or I52,hasbeenien aged, current Wiljl bfi delivered to the motor I43 of theyrna-inthrottle, and rotation thereof will commence,

tive direction;

,rocking such main throttle in the proper correc- Such correctiverockingof. the

main throttle will continue untilcomplete synchronism has been attained,and due to thc fact that the operation of the main throttleis 'fast, ina corrective sense, there will probably occur a slight over riding ofthecorrective influence, so thatthe condition of synchronism will-beslightly passed or exceeded. Thereupon-a further corrective; action in.the reverse directlonnoi the trimming throttle will occur, and assoon assuch trimming throttle moves slightly back from its extreme position,the contact I5!) will move away from the contact I5I or I52, as the casemaybe;

so that further operation of the main throttle main throttle. This shaftI 4| is connected to a will cease, and the final trimming action willbeefiected by the trimming throttle, leaving the main throttle in itsnewly established position.

Now it was mentioned that the worm gear, I42

is frictionally mounted on theshaft I4I of the suitable manual controlfor eithersingl or. gang control of the main throttles by theplanespilot,

as will presently appear; and duringsuch man- ;ual controlit isnecessary to rock the main would be effected.

desires of the pilot of the plane. strument I68 is provided to indicateaccording to thisfrequency, but said instrument'willgen- "erally becalibrated to read in R; P. M. direct.

aeiaese throttle" notwithstanding that the'motor I43 and worm gear I42are not rotating at the instant. 'Such "result may be effected by thepresence of wormgear-Ifl. H j Referring to Figure 1 I have therein shown'the several main throttle shafts I'M as being conhe'irictiondrivebetween the shaft Mi the 'also'provided a gang control element 16!to which any one'or all of these control r'odsm'ay be connected,""as bythe'u'se'of set screws or the like, scr m by single manipulation of thisgang con- Itro'l element all the" main throttles may be'simultaneouslycontrolled manually; orcQnVersely, any one or-more of them may bereleased from such" ga'ng' control'y and individually manuallycontrolled. Now it is noted that during automatic control forsynchronism these control rods should be disconnected from the gangcontrol device sothat as'the several main throttles are called ontorockunder automatic control, such rocking may-occur for each mainthrottle in'di- "vidually, In case of a condition inwhich all thesynchronous control automatically should be accomplished by use of 'thetrimming throttles,

the gang control in the foregoing manner, and still automatic controlforspeed and synchronism jY Each of the polyphase windings of thesynpilot alternator I29 connect directly to the bus bars 166, so thatthese bus bars are excited at all'times at frequency equal to themomentary frequency being delivered, and according to the A suitable'in-There are provided separate three pole triple throw switches I69, I10,HI and I12, corresponding to the several power motors which are to besynchronized, and the blades of these switches connect directly to theseveralthree-phase'lines I62, I63, I64 and I65, respectively, for theseveral power motors. One'set or contacts for each of these'switchesconnects to the bus bars I56 (see Fig. 1 another set of said contactsconn ects 'to thebus bars 161, and the third set of-said contacts isdead, corresponding to the off position of the switch. Thus, either setof three-phase lines I62, I63, I64 and I65 may be -individually switchedeither to the oiT or dead position, or to either set of bus bar's, undermanual control of the pilot of the plane; A phasing or timing instrumentI13 is connected to the busbars I61, said instrument reading similarly.to the instrument I68, for example, in

"speed, by requirement for synchronous condition with respect to thefrequency'being generated as determined by the planes pilot. However, ifdesired, any given power motor maybe instantaneously cut ofi from suchautomatic control by merely switching its switch tothe off position (orelse to the busbars I61). For 'example, in'case of damage to any powermotor same may be cut off from the automatic synchronizing system inthis manner. Furthermore, when bringing in any given power motor whichmay have been idle, it is desirableto get it to a speed approximatingthe momentary speed as dictated by the setting of the pilot circuit,under control of the planes pilot. Thereby any violent reactions duringinitial or starting condition may be avoided. To thisend,

when a power motor is-to be brought to 'the'automati'c speed controlcondition its switch I69, I10, IN or I12 may first'be thrown to thebus'bars I61, andsuch motor may then be manually brought ,to a. speedapproximating that indicated by the instrument I68 (that is, the 'speedofthe incoming power 'motor as read on the-instrument I13 may be broughtclose to thespeedindicate'dfby the instrument I68, and then the switchfor the incoming motor may be thrown to the bus bars), whereuponautomaticcontrol of such'power motor for speed will'beassumed by thesystem. I t

The following operating condition is also to be noted;

If for any reason the pilot frequency threephase circuit I21 should fail'(due for example to failure of the pilot alternator, or to failure ofsome other portion of this system) it-would be possible to disconnectany or all of the power motors from the bus bars 166 and/or I61 byproper-movement of the switches I69, I16, HI

and I12, then relying entirely on manual and individual speed control ofeach power motorindividually. Or, under these or other conditions whichmight arise all the switches or anyselected grouping of them mightbethrown to one or the other set of bus bars, so that theinterconnectionofthe speed control devices of two or more of the powermotors would be created. Then any given power motor might be selected asa pilot motor, its speed being manually andindividually controlled bymanual throttle'operation by proper disconnection from the gang controlI6I. Then such pilot power motor would rotate its control device at aspeed proportionate to the speed of such power motor, andfdue r toexcitation of the field of such control devicethere would be generated afrequency proportionate 'to the speed of such power motor,

such control device acting as an alternator and deliveringthree phasecurrent to the bus'bars at a frequency determined by the manual controlof such pilot motor, and bringing all the other power motors intosynchronism with such pilot motor insofar as respects speed condition.In this connection any of the power motors might be thus selected as" apilot motor under such conditions; and all orany selected groupoftheremaining power motors might be switched into speed controltherewith.

It is to be noted that under the foregoing conditions the three phasewound element or stator of such control device should be locked againstrotation during such pilot control operatiomso that a proper reactioneffect could be produced for generation of the three phase pilot controlcurrents. To this end I have tion when the plunger has come to its newposition as dictated by such control sleeve movement. Pressure oil issupplied to the device through the port I92, and released oil isdelivered from the device through the ports i93 and I94.

Now in the layout of Figure 17 I carry oillines I95 and I96, forpressure and release, respectively,

from the oil system such as heretoforedescribed in connection withFigure 1, to the several servo motor locations; and these lines areconnected respectively to the proper ports of the several servomotors,so that the blade shifting devices thereof may be power operated by suchpressure oil.

Corresponding to the several power motors, and

V to the servo-motors thereof, are the small control cylinders I91,having the plungers I98. These plungers are connected to the controlrods I90 of the several servo-motors, so that by oil operations of theseplungers I98 the control rods of the s'ervo-motorsare also operated tocause corresponding. placement. of-the servo-motor plungers, and thusalso power functioning of the blade shifting devices. There. areconnected to the ends of the small cylinders I91 the oil lines I99 and200, for each of said cylinders, and these oil lines follow to thecontrol valves 20I, 202, 203 and 204 for the respective power motors.-The constructions of these valves will be disclosed presently herein.These arrangements provide for manual control and adjustment of theseveral propelle'r blades by use of pressure oil and from a commonstandor location. I

I have also made provision for automatic con trol and adjustment of theblade pitche'saccording to power requirements or adjustments. These Ishall now describe,

The fuel meter I11 of" the pilot" power motor is connected to asmallpolyphase alternator 205, excited by direct current in the wellunderstood 'manner. An indicating meter 206 is provided: in connectionwith the polyphase lines 201 leading I from this pilot alternatonshowing either frequency or power or some other function, as desired.The polyphase lines 201 extend to locations close to all the otherpoweri'notors. Adjacent to eachlQ the fuel. meters for each oftheseother power motors are the synchronous control devices, such asalready described in detail, and shown? in Figuresand 11 hereof. I Thedirect current field of eacncr these control devices is connected totheshaft of the corresponding fuel meter, and therefore. rotates at thespeed thereof; and the polyphase element. of each of these controldevices is connected to theflines 201, and

therefore has generatedin it a rotatingfield proportionate to thefrequency of the polyphase current being supplied thereto, and thus alsoproportionate to the rate of fuel consumption (power) being generated bythe pilotfpower motor. The polyphase element of each of these controldevices has its shaft worm gear connected to a segmental rack 208, sothatsuch rackfis rocked in one di rection or the other according, to thedifferential between the speeds of the frequency on the-lines 201andthefuel meterof the I mounting for each oithe control devices of thethe pressure oil line I95.

power motor in question} Connected. to each segmental'rack 208 is an-arm 209 which will swing back, and-forth accordingto controlled rackmovemen-tss There is a lever arm 210, pivoted at 2| I, for each-sucharm209; and a pin and slot connection 212 is provided between each of thelever arms and the corresponding arm 209. Furthermore, there is a pinandtslot connection 2I3 between each ofthe lever arms and the controlrod I-of the corresponding servo-motor. Thus it. is evident thatmovements of the :control rod I90 of theservo-motormay be effectedeither by mally, meshed with the worms of the control device shafts.Such condition is that shown in Figure 1'1. When,- however, it isdesired to effect manual control of theblade shifting, by suitableoperation of the valve 20I, 202, 203 or 204, as the case may be, it isnecessary to-disconnect the segmental rack 208 from the shaft wormof thecontrol device, in order that such segmental rack may be swung in onedirection or the other under such manual control. To this end I providea pivotal fuel meters, so thatsame may be swung down to disengage itssegmental rock. from the shaft worm, during gsuch manual control. Then 1provide a small cylinder 2 I4, having the plunger-2 I 5, for eachcontrol device, and the plunger rod 2I6 from such plunger reaches to thecontrol device shaft, so that said rod controls the engagement anddisengagements ofthe control device shaft with and, fromthe segmentalrack. A spring 2I1 serves to restore :the engagement of. the shaft wormwith the segmental rack. for normal opera- I tion. There. is an oil line2I8 connected to each of these. small cylinders. 2M; and such oil lineis carried to the. corresponding. control valvev 20I, 202, 203 or 204,asthe case maybe, so that-pressure oil is admitted to such smallcylinder harmoniously witha manual control operation, in order torelease the segmental rack from the shaft worm, and permit such manualoperation without interference from the presence of the automaticcontrol device. I,

Reference to Figures l3, l4, l5- and 16 shows the construction of one ofthe control va1ves20I, 202, 203 or 204,asthecasemay be. This valveincludes the cylindrical casing 2 I9 wherein the plug valve 220operates, said plug valve having the stem 22I passing out through thepacked gland 222, and said stem having the control handle 223. At a highlevelthe housing 2 I 9 is provided on one side with the ports 224' and225, to receive the lines I99 and200, respectivelytwhichlead to themanual control cylinder I91 of the corresponding power motorinstallation. On the. opposite side of the valve housing and at the samelevel is the pressure oilsupply port226 to which is connected At a lowerlevel the housing 2!!! has the port 221 beneath the ports 224 and 225and centrally between them; and at this lower level, and beneath theport 226 is the discharge port 228 which connects to the oil return lineI96. The valve plug has the. segmental opening 229 which registers withthe pressure supply port 226,.and-a passage. 230 extends from thissegmentalopening to the opposite side of the shown the shaft 60 of eachsuch control unit as being provided with a small brake drum 60 withwhich a brake band 60* may be co-optation as long as the solenoid 60 isenergized by direct current supplied over the leads 60 and se thearmature (W of such solenoid acting, during such energization, totighten the brake band and lock the element 59 against rotation.

vided a very flexible arrangement for speed controls of the severalpower motors, and have provided insurance against any adverse conditionswhich might arise in operation. This is especially important inconnection with such inulti-motored planes as are used in military ornaval or like operations.

Reference may now be had to Figure 17 wherein I have incorporatedcertain of my features of invention in an arrangement wherein no specialpilot circuit is provided for generating polyp-hase current of apre-determined frequency to control the speeds of the severalpowermotors.

In the present case one of the power motors, for

example, '12, is used as a'-pilot:- motor for speed control. To this endthis particular power motor is speed connected to a special smallthree-phase alternator I'M, which supplies polyphase pilot current forthe speed control operations of the other power motors, in mannersimilar to that already explained with respect to the general scheme ofFigure 1. It is deemed'unnecessary to explain in full detail all theconnections and devices of this portion of the disclosure (if-Fi ure 1?,as same have been fully gone into With respect to the arrangement ofFigure 1.

However, in the arrangement ofFigure 1'7 I have, in addition toprovision for control'of speed and synchronization thereof, madeprovision for control and synchronization of powers of the several powermotors. To this end I have provided for measure of the momentary powerbeing delivered by each power motor, so that same may be compared withthe powers being delivered by the other motors (or with asuitable pilotpower circuit, as will be hereinafter described). Any suitable form ofpower metering device may be used in connection with each power motor;but generally speaking such power metering devices require measurementof torque and speed, and proper co-relation of these factors As asimpler expedient and one which will effectively and accurately conformto the requirements of the present problem, I prefer to provide a fuelmetering device or meter in the fuel line leading to each power motor,such, for example, as well known metering devices of the plunger or eventhe nutating plate types which are well known in the metering arts. Byselection of a meter of proper and suitable size consistent with thefuel flow requirements of .the power motor, when said motor is operatingat its usual load conditions, it is possible to secure very accuratemeasure of power being delivered by'such power motor, by making use ofthe rate of shaft rotaerated to lock the wound element 58 against rotionof the fuel meter. In the case of the relatively large sizes of powermotors being currently used on airplanes and the like (upwards of one totwo thousand horse-power), and when said power motors are operating atpowers of over, say, one-fourth their rated output, it will be foundthat the rate of meter shaft rotation will very closely follow or be adirect function of the delivered power. While it is true that the actualhorse-power output of such power motor will depend on variousconditions, such as octane rating of the fuel being used, atmospheric orsuper-charger pressure, etc., still it is nevertheless true that therate of meter shaftrotation will be directly proportional to the rate ofpower delivery, and therefore such rate of shaft rotation will be aproportionate measure of power being delivered by such power motor.

Furthermore, in the case of a multi-motored airplane, in which all themotors are receiving fuel from the same source of supply, or from thesame fuel line, it is evident that as between these various motors therates of rotation of the shafts of their several fuel metering deviceswill be a Very accurate means of determining the relative power outputsof the several power motors at any given instant; and therefore suchmetering devices constitute a very simple and accurate means formeasuring or comparing power outputs of the several power motors forpurposes of power synchronization and for other purposes, as willhereinafter appear.

In the layout of Figure 17 I provide a fuel supply line I15. receivingfuel under pressure from the fuel pump [76; and for each of the severalpower motors I provide a fuel meter Ill, same being placed in the fuelsupply line leading from the main fuel supply line ll5 to thecarbureting device or devices for such power motor. The shafts H8 ofthese fuel meters therefore rotate at speeds proportionate to the powersbeingdelivered by the several power motors.

The propeller of each of these power motors is provided with servomotormeans to regulate or control the pitches of its blades. These servomotordevices are shown at I19 for the several propellers. Each of theseservomotor devices is of such construction that when its control valveis movedto a given position or adjustment, its plunger will be moved byoil pressure to an exactly corresponding position, and will be oillocked at such position until a new setting of its control valve ismade. A typical servomotor responding to such requirements is shown inFigure 12, and is also shown in Letters Patent of the United States, No.1,642,193, issued September 13, 1927, on my application. This servomotorincludes the casing or housing I80, including the end caps 18! and I82.The power motor shaft I83 extends through this servomotor from the powermotor to the propeller hub. Within this housing and surrounding the,power shaft I83 is the annular plunger I84; and thesleeve I85surrounding the power shaft I83is connected to this plunger and passesout through the end cap I82. Said sleeve connects to the blade shiftingdevice inthe propeller hub, so that back andforth movements of saidsleeve serve to control propeller blade pitch.

tions.

. 21 plug, and at the higher level thereof. Onthe sides of the plug atthis higher level are the arm-- ate cut away portions 23I and 232 whichregister with the ports 224 and 225, respectively for all pohousingports 234 and 235 which connect by the.

passage in the housing 236 with-the port 221 from both sides thereof.The segmental cutaway portion 233 connects with a space 231 beneath theplug; and extending down on the sidesof the plug, normally in registerwith the ports 234 and 235 (when the plug is in its central or normalposition) are the slots238 and 239. Likewise the slots 249 and-2M extenddown along thesides of the plug from the Segmental cut away portions 23Iand 232 to the space beneath the plug.

With this form of plug valve the following conditions will exist; I

When the valve stands in the position shown (central), pressure oil iscut off from all lines I99, 209 and 2I8. Also, at such time all theselines are relieved and are connected to the oil return line I99; andalso both of the lines I99 and 230 are connected together at theposition of such valve. Upon turning the plug in one direction or theother, either the line I99 or the line 299 will be connectedto the oilpressure line I95, and theline 2! will also at such time be connected tosuch oil pressure line; and the other.

of such lines I99 and 209 will be connected to the oil return line. I

It is also noted that with this valve arrangement, when the valve plugstands in its central positionboth of the lines I99 and 200 areconnected together, so that during automatic control bymeans of thecontrol device (synchronous), the plunger I98 ispermitted free movementin either direction under action of the control device, and without oillock, for automatic opera- Suitable gang control devices are provided inconnection with the valves 211i, 202, 293

and 204, so that if desired all these valves may be operated in gang, orany group may be so operated, or they may all be operated singly.

With the arrangement of Figure 17 the "pilot power motor is normallycontrolled manually by I power meters being controlled by throttlecontrol, and the power of each of said otherl ower motors beingcontrolled by control or the pitch of the blades of its propeller. I

In the layout of Figure 18 I have departed from that of Figure 17 in thesense that in Figure 18 I have provided a special motor-generator, al-

ternator unit 240*; whose frequency is under control of the pilot of theplane; and this unit delivers current to the pilot threephase lines 2I'I for control of one function of all the power motors. But in thepresent case, also, thefuel meters are connected to the motor throttles,and with the control units operating in conjunction therewith,forsynchronization of powers ofthe power motors by throttle control.Furthermore,

in the present case one power motor serves as a pilot motor for speedcontrol of the other. power motors by control of pitches of thepropeller blades. To this end said'pilot motor drives the small threephase alternator 242 at speed proportionate to power motor speed, saidalternator trol of the pitches of the bladesof said pilot power motor. 1

In the layout of Figure 19 I have provided two pilot three phasealternators, direct current mo tor driven, for providing pilot'threephase circuits for both speed and power of the power motors. These arethe units" 244 and 245, respectively. They serve the pilot three phaselines Band 241, respectively; and these pilot lines-servethe severalpower motors for control of speed by throttle control, and control ofpower by blade pitch control, respectively. The details of all thesefunctions will be well understood from the disclosures hereinbeforegiven.

In the layout of Figure 20 Lhave also provided the two pilot motorgenerator units 248 and 249,

g respectively, for-control of power and speed, re-

not require detailed description, in thelight of the previousdisclosures made herein.

Generally in the operation of the airplane it will be desirable toset'the power motor speeds, and then hold them at such settingautomatically by the speed" controls; and the power settings may bechanged from time to time by manipulation of the pilot power motorgenerator set. Such operation may be admirably secured by such a layoutas that of Figure 19, for example. In the service operation of such alayout as that of Figure l9, assuming that the speeds have beenadjusted. and synchronized to correspond with the pilot speed circuit,the throttles will have been brought to such conditions that the severalpower motors are delivering the demanded powers, as dictated by thesetting of the power control circuit, each -propeller having its bladesbrought to'pitch conditionto absorb the prescribed power at the speeddictated by the speed control circuit. Now if the power factor bechanged, for example increased, by a new setting of the control circuitfor power, by, increasing blade'pitches, a reduction of speed willmomentarily occur, and this will at once-cause the several motorthrottles to move further open, and thereby restore the several motorspeeds to the prescribed speed. Thus, although the power controlsoperate on the bladepitchcontrolmechanisms' directly, still the ultimateresult of power control is to also reflect into the throttle settings,since the power-in fact comes from the consumption of fuel deliveredthrough said throttles.

Considering again the matter of measurement of power by measurement ofrate of fuel consumption, it will be-noted thatin each of the layoutsherein disclosed all the power motors are supplied with fuel from acommon line, so the'yall consume fuel of the same octane rating andother characteristics at any given time. Due

- to this'fact, among others, it follows that if all the power motors beconsumingfuel atthesame made ineffectiveby the pilot of the plane.

:aaracuc rate, all said motors being of the same design andsize,..etc.,' all said motors will be delivering power atthesamerate,that is, operating atthe same power, within a very slightpossible,error. Now, it is to be noted that insofar as concerns speed control,thisv factor (speed) will beyaccurately controlled irrespectiveofslight'difierences of power delivery as between the, several, powermotors, since the speed of each; power motor is controlled with directreferencetoa specified speed or, frequency of the control circuit.Therefore, speed will always be very accurately maintained with respectto synchronism,irrespective of any slight departures from exactsynchronization of powers. This is an important feature of the. presentinvention.

It is also to be noted that when speedls held uniform as between all themotors of the series, if power also be held uniform as between all saidmotors there will be assurance that all the propellers are demanding thesame torques, their several pitches being brought to such regulationsthat this result is secured. This means that with control of both speedand power for uniformity as between all the power motors, tnereis assurance that the pulls of all the propellers are the same, so that anytendency of the planeto yaw is avoided. Simplicity of plane control istherefore provided by control of bothspeed and power, and danger ofsudden loss of control in an emergency is greatly reduced. 7 3/ It isnoted that change of angle of attack of the elevators of l the airplanefor purposes of climb or descent/in elevation are accompanied by changesof pull necessary to tbeqexerted by the blades of the propellers; 'andtherefore increaseof rateof rise .ofjthe plane (according to change ofelevators), or decrease of rate-oi rise (or in other words descent) oftheplanashould be accompanied "by suitable changes in the propellerblade pitches. I have in'thepresentcase made provision for such results,and have also tied up these changes in function with changes in motorpower of corresponding nature, Lam able to do this automatically in thepresent case as I have madeprovision for power controls as hereinbeforeexplained. 4

Reference to Figure 18 shows the elevators of the plane in diagrammaticformat 250 and 25!; and in that figure the control'stick-is shown at 252for controlling said-elevators in usual manner. I have in that figurealso shown'the connection 253.from the control stick 252 to the plungerof the oil cylinder which controls the-setting of the propeller bladesof the motor -12. connection it is evident that as the elevators areshifted to cause the plane to-rise ordesoend the pitches of thepropeller blades will'be correspondingly changed so that change of rateof rise or descent of the plane will be accompaniedbycor respondingchanges in blade pitches ESince-I have made provision for control ofpitches of the the blades of the other'propellersfrom-,motor-JZ totheother motor propellers, it"follows that all the propellers will havetheir blades properly.

With this speed control; and that. one of the elements of such speed.control unit is drivingly connected,

either tofthe power motor shaft, or to the shaft of Ithe metering unit,the other element being actuatingly connected with either the throttleor the control valve device for the servo-motor which serves thepropeller blade shifting device. Also, that inall cases the polyphasewound element receives polyp-hase current of controlled ,-.-frequency,and the other element is excited with direct-current to produce,definite poles whose position is fixed with respect to such element. It.is, also noted that in every case, when there is aideparture fromsynchronism as between the controlled speed, and the speed 0: therotating element (eitherpower motor shaft or meter scheme for the bladeshifting device); and that furthermore, in all cases the operationissuch that, as correction, occurs due to such rotation caused bynon-synchronism, the rate of such correction decreases progressively,froma maxi mum at the commencement of the corrective action,to zero whencomplete correction has. been attained. This is to be distinguished fromprevious schemes and arrangements in which relays have been used, orlike devices, and in which the rate of correction remains constant fromits shifted from time to time harmoniously with shifts of the elevators.I have provided a disconnectable connection 254 in the connection 253 sothat if desired this interconnection may be It is to be noted that ineach of Figures 1, l7, 18, 19 and 20 use is made of one of the controlunits shown in Figures 1 0 and 11, and with at least one such unit foreach power motor, and

beginning until the complete correction has been attained (synchronism)whereupon there will be ,anover-jriding eifect, requiring correctionback and forth until finally something approximating 'synchronism hasbeen secured. This result is possible in mypresent arrangements, due tomy use: of control units each having two reactive elements one of whichis capable of generating a rotating, field 'of angular velocity.proportionate toa supplied current frequency, and the other of whichreactive elements has definite magnetic ,polesof; angular position fixedwith respect to useand application of the features of my presentinvention either with vapor fuel motors, such as gasoline engines, orliquid fuel motors, such as diesel type engines, or many other types ofengines'ormotors; such as steam, etc. Where in i this specification, andthe claims to follow I use such termsas throttle I contemplate anysuitable form 'of control throttle or valve for anysuch motor, as willbe readily'apparent from the nature of my present invention.-

" liiythe terms fuel control throttle, or throttlemeans, or fuel supplythrottle, or like terms as used in the claims 'Iflcontemplate any fuelsupply control or delivery means, for controlling the supply or deliveryof the liquid fuel, to a power I diesel or two-cycle type in which theliquid fuel vlis forced into the cylinders under pressure; and

whether'isuch fuel supply control or delivery .meansbe the throttle orthe liquid fuel meterwithrcertain of said units in connection withgsgfill gtm an .f r-Supplier liquid fuelto the cylinders under pressureand in metered'quantities at each stroke. i It is noted that power is afunctionof the product of speed times torque, or of velocity timesreaction; so by synchronizing both power and speed we have made itpossible to also synchro nize torque or to synchronize reaction againstthe body of air wherein the airplane is-travelling.

26 fuel metering means foreach power motor, each such fuel meteringmeans having a shaft rotatable in proportion to fuel consumption, apolyphase electro-magnetic control device for each power motor, eachcontrol device including a polyphase Wound element and a fixed polefield element, means to drivinglyconnectsaid ele- Such result is ofgreat value for the purpose of facilitating the control of largeairplanes and those having numerous power units and propel lers. By suchsynchronization of torques or reactions it becomes possible for thepilot or engineer to equalize the pulls (or pushes) of the numerouspropellers of a multi-niotored or multipropellered airplane, and thus toimprovethe control thereof under varying conditions. This feature,combined with the ability to take over manual control of any unit whenthe occasion or desirability arises, becomes of great value in the caseof planes of large power, and many power units.

Iclain'l:

1., In an airplane havingja plurality of power motors each of whichisprovided with a fuel control throttle, and a variable pitch propeller,

means to control and 'synchronize said; power motors for speed,comprising means undercontrol of the pilot of the plane to generate acon trollable frequency polyphase pilot circuit current, apolyphasereactive electro-magnetic control device for each power motorincluding two reactive elements, one being a polyphasewound element andthe other being a fixed pole field element, means to journal both ofsaid reactive elements for 360 degree rotation about a common axis,means to connect said polyphase wound elemerit with said polyphase,pilot circuit current; and means to drivingly connect one reactiveelement of each control device with the power motor shaft of a powermotor, and slip drive means to connect the other reactive element ofsuch control device with the fuel control throttle for such power motorto shift said throttle according to differential of frequencies of thepolyphase pilot circuit current and the'speed of the powermotor shaft,substantially as, described. 7

2. In an airpianehaving a plurality of power motors each of which isprovided with a fuel control throttle, meansto control and synchronizesaid power motors for power, comprising an eleci-ro magneticdifierential device for each power motor, and including two reactiveelements, one of which is a polyphase element, means to meter fuel asdelivered toeach power motor individually, means to drivinglyccnnect'said elements, one to the power motor metering means of eajch'power motonand the other {to the fuel throttle of such motor, means togenerate a polyphase pilot circuit current, means under control of thepilot of the plane to control the frcquency of said pilotcircuitflcurrent,and means to supply said controlled frequency polyphasecurrent to saidpolyphase elements substantially as described. I

3. A system as specified in claim 2,wherein there are provided means tomanually control the throttle of each power motor, and means to makeineffective the differential device foreach; power motor, selectively,substantially as described. i

4. In an airplane having a plurality of power motors each of which isprovidedwitha 'fuel' control throttle, means to controland synchro-'-nizc said power motors for power, comprising current to said polyphaseelement substantially as described.

5. In an airplane having a plurality of power motors each of which isprovided with a fuel control throttle, means to control ,and synchronizesaid power motors for power ccmprisingfuel metering means for each powermotor, each such fuel metering means having a shaft rotatable inproportion to fuel consumption, a manually con trollable pilot frequencygene-rating device, and differential means in connection with the shaftof the fuel metering means of each power motor and said pilot frequencygenerating means and the fuel control throttle of such power motoreffective to maintain synchronism between the pilot frequency generatingmeans and the shaft rotations of the fuel meteringnieans by variationofsaidfuel scribed.

6. In an airplane having a plurality of power motorseachof which isprovided with a fuel control throttle, means to control and synchronizesaid power motors for power, comprising fuel supplymetering means foreach power motor having an element movable at a rate proportioncontrolthrottlasubstantiaHy as (15? ateto the rateof fuel feed to such powermotor, and synchronizing means including the power motor throttlesand'said movable elements of the fuel supply metering means effective tovary the throttles of the power motors accordingtothe rates of movementof said movable elements, effectively to maintain synchronism of saidrates of movement, substantially as described,

7. In an airplane having a plurality of power motors each of which isprovided withthrottle means ,to control supply of motive iiuidthereto,

means to control and synchronize said power motors'for speed comprisingan electrical differential control unit for each power motor havingtworeactive elements one of which iscapable of generating a rotatingfield of angular velocity proportionate to a supplied current frequency,and the other of which reactive elements has definite magnetic poles ofangular position fixed with respect to its physicalbody, means tojournal both said reactive elements for free rotation with respect toeach other and with respect to the power motor controlled bysuch controlunit, a positivedriving connection between one reaction betwee the otherreactive element and the throttle means of such power motor, and manualmeansto control the throttles of the power motors independently of eachother, together with means to lock the rotatingfield element of'aselected control unit against rotation to thereby causesaid controlunitto act as a polyphasc pilot generator for supply of controlpolypnase current

